The invention relates to a turbocharger having a turbine to which exhaust gases can be supplied from two channel ducts between which there extends a partition, a so-called channel separator, in which a closable channel connection opening is formed. Moreover, the invention relates to a motor vehicle having such a turbocharger.
Exhaust-gas turbochargers are known in which a turbine is fed from two channel ducts, i.e. two exhaust-gas flows separated from one another. The two channel ducts can be selectively connected to one another via a channel connection opening, i.e. a closable opening. In the case of a four-cylinder internal combustion engine, for example, one of the channel ducts channels the exhaust-gas flow from the 1st and 4th cylinder and the other of the channel ducts channels the exhaust-gas flow from the 2nd and 3rd cylinder to the inlet of the turbine of the exhaust-gas turbocharger. In a low-load range, it is advantageous if the channel connection opening is closed such that pulsations of one cylinder are not transmitted to the other cylinders. Moreover, with regard to a single cylinder, the closed channel connection opening leads to a narrower cross section of the exhaust-gas flow from the cylinder to the turbine inlet, resulting in better energy utilization in the low-load range. In the nominal or high-performance range, a larger cross section is advantageous, and so the channel connection opening is open and thus the exhaust gases coming from one of the cylinders can flow downstream of the channel connection opening in both channel ducts (cross-sectional enlargement). This also means that the exhaust-gas counterpressure can be reduced in the nominal performance range.
Previous channel connections are embodied either as a throttle flap, as a flap valve or as a disk valve. These solutions have the disadvantage that they can influence the flow progression because, even in the open state, they project partially into the flow, or relatively complex measures are required to avoid this. Another disadvantage is that the previous solutions demand a large space requirement.
It is therefore an object of the invention to provide a turbocharger with a connection of the channel ducts that has advantageous flow properties.
According to one exemplary embodiment of the invention, there is provided a turbocharger having a turbine to which exhaust gases can be supplied from two channel ducts between which there extends a partition in which a closable channel connection opening is formed, wherein the channel connection opening can be closed by a panel-shaped slider which can slide along its panel plane between the channel ducts. This exemplary embodiment has the advantage that the slider allows a situation in which the slider is arranged laterally with respect to the ducts and as a result can be configured with a large diameter and to be sufficiently long in order to ensure good actuation and good sealing without negatively influencing the flow. In the open and closed state of the slider, no disturbance bodies are situated in the two channel ducts. With the slider open, the crosstalk flow can be made very favorable by the directly adjacent position of the channel ducts. Overall, more favorable flow conditions can be achieved than in the prior art. The use of a slider and the thus possible external position means that the guide can be provided with the required guide surfaces and plays and jamming can thereby be prevented. Moreover, the guide, by virtue of its external position, is removed from the relatively high temperatures. Furthermore, gas forces are for the most part perpendicular to the direction of movement of the slider, resulting in low retaining forces in the displacement system.
According to a further exemplary embodiment of the invention, in the closed state of the slider, a front end of the slider is arranged within the channel connection opening and an outer surface of the slider bears against an inner surface of the channel connection opening.
According to a further exemplary embodiment of the invention, the slider tapers toward a front end in its panel plane and traversely to a sliding direction. The advantage of this exemplary embodiment is that, by virtue of this shape, the slider is released from the inner surface of the channel connection opening directly after the start of the opening movement from the completely closed position, with the result that an effortless opening actuation is made possible and jamming between slider and channel connection opening is avoided. Furthermore, this shape allows a situation in which the slider, in the closed state, can bear with prestress against the entire inner surface of the channel connection opening.
According to a further exemplary embodiment of the invention, of an inner surface of the channel connection opening and of an outer surface of the slider, one is formed concavely and the other is formed convexly. The advantage of this embodiment is that the slider is thus guided during the closing operation and, when the closing operation takes place, the outer surface of the slider engages in the inner surface of the channel connection opening. In addition, with the slider in the completely closed state, the inner surface can thus take up forces in the direction of the z axis.
According to a further exemplary embodiment of the invention, the turbocharger further comprises a housing, in which the channel ducts are formed, and a cover which can be fastened to the housing and in which at least half of the slider is accommodated in the opened state of the channel connection opening.
According to a further exemplary embodiment of the invention, the turbocharger has a sliding element at one end of which the slider is formed and which has a panel-shaped guide plate whose panel plane is perpendicular to the panel plane of the slider, wherein the guide plate of the sliding element limits a sliding movement of the slider.
According to a further exemplary embodiment of the invention, a guide disk is arranged between the cover and the housing, which guide disk is pressed against the housing by the cover and which has a guide gap whose dimension in a direction normal to the panel plane of the slider substantially corresponds to that of the slider. One function is that of sealing the channel ducts with respect to the cover or at least that of reducing the inflow of exhaust gas. In addition, the guide disk 15 serves as an antirotation safeguard for the slider.
According to a further exemplary embodiment of the invention, the guide plate is guided by an inner surface of the cover. Consequently, the cover performs both guiding and sealing functions.
According to a further exemplary embodiment of the invention, the sliding element has, on the opposite side to the slider, and with respect to the guide plate, a guide shaft which is surrounded by a guide sleeve which in turn is held by the cover.
According to a further exemplary embodiment of the invention, an actuator rod for actuating the sliding element by means of a ball joint engages in the guide shaft. The attachment by means of a ball joint makes it possible to compensate for manufacturing or installation tolerances.
According to a further exemplary embodiment of the invention, the guide plate has through-holes or grooves, which grooves are incorporated on its outer circumference. Consequently, pressure differences during opening and closing of the slider are avoided.
Moreover, the invention relates to a motor vehicle having a turbocharger as claimed in one of the preceding claims.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.